SECT. 5] 



DEEP-SEA ANCHORING AND MOORING 



523 



Experimental vertically tending elastic pennants are now being tested. The 

 pennant is made of nylon-covered shock cord with the instrument line married 

 to it at intervals in S -shaped loops. 



Advantages of the latter system are that only one line is used for both 

 mooring and recording, and the terminations of the instrument line remain at 

 an approximately constant depth as the scope increases. On the basis of recent 

 tests, this system appears to be successful. 



C. Subsurface Floats 



The subsurface floats have usually consisted of spherical steel tanks (com- 

 mercial butane tanks) of approximately 3-ft diameter and |-in., or greater, wall 

 thickness. Some cylindrical steel tanks have been used. In use, the subsurface 

 floats are normally pressurized to about the ambient pressure at their proposed 

 depth. In a recent test (February, 1958) an unpressurized spherical steel tank, 

 34 in. in diameter and having a wall thickness of - 3 - 2 - in., survived submersion to 

 a depth of 500 m. 



The drag of the submerged float is small in comparison with the other drags 

 of the system and streamlining has not been contemplated. Streamlining 



Pennant to surface 



Mooring wire 



Fig. 4. Yo-yo buoy — two views. 



involves an asymmetry and orientation in the system that is disadvantageous 

 where any wave action occurs because the float will continuously rotate. 



An interesting modification of the spherical buoy is now being tested that 

 will pay out an additional wire as soon as the maximum working stress of the 

 pennant is reached, thereby allowing added scope in extreme weather and also 

 permitting the recovery of the pennant and instrument wire by merely pulling 

 on it. This float functions as shown in Fig. 4 and has been called the Yo-yo 



